NOTES for Luk 4:38-44
Why do three evangelists give attention to this one of Jesus' first miracles, the healing of Peter's mother-in-law? Perhaps the reason lies in the genre of the Gospel: testimony. Testimonies are strong and convincing when they are not anonymous, when they speak not in general about some healed people whom the witnesses themselves never met, but about concrete people known to the listeners or close to those whom they know. Everyone knew Peter, and his mother-in-law is a very concrete and convincing example.
It is interesting that all three evangelists emphasize one detail: "She immediately rose and served them." This does not mean, in all probability, that such behavior was uncharacteristic of her. Rather, the point is that miraculous healing is given to a person not without purpose, for God does nothing without purpose, but for service, because this is exactly how love expresses itself in behavior.